Compatibilized polyphenylene ether-polyamide compositions are thermoplastic blends which combine a number of useful properties from each of the basic components.
Polyphenylene ether resins (PPE) are known to have good thermal properties, impact strength, hydrolytic and dimensional stability, as well as good electrical properties.
The polyamide or nylon resins offer good chemical o resistance, process ability and impact strength.
PPE-polyamide blends have found great utility in thermoplastic applications which require a combination of these properties. For example, PPE-Polyamide compositions can provide automotive body panels which are readily injection moldable on typical molding equipment. These compositions exhibit the good impact strength and ductility necessary for such large automotive parts and can withstand high oven-aging temperatures when body panels are painted on-line in existing automotive paint ovens.
It has now been discovered that PPE-polyamide compositions can be effectively stabilized with certain metal salts such as metal halides which will be described in detail below. Such stabilized compositions exhibit several improved properties including retention of impact strength properties after heat aging, resistance to oxidative degradation and, notably, an enhancement in melt stability.
It is especially with regard to these last two mentioned properties that the PPE-polyamide compositions of the present invention differ from stabilized polyphenylene ether resins or polyamide resins. The present PPE-polyamide compositions are stable during the high temperature, molten conditions of modern extrusion and molding processes, and resist the tendency toward degradation of the resin often encountered in such processes. This property is of particular significance when it is desired to provide stable resins for the large part thermoplastic applications mentioned above such as automotive body panels. For example, cuprous iodide will improve the chemical stability of the PPE-polyamide blend at melt processing temperatures. This is a critical feature since the material must give good mechanical properties under a wide variety of melt processing conditions. Improved stability in the melt allows higher processing temperatures to be employed. A direct result of this is improved melt flow, which allows the use of less costly equipment for molding and facilitates the fabrication of larger parts.